


Dark Trees, Cold Barks, Flitting Shadows

by AKA_Indulgence



Category: Undertale (Video Game)
Genre: (i dont mention it in the fic but.. yeah nightmare kinda hypnotizes you with his voive), (or magic), Dark, F/M, Female Reader, Hypnosis, Kidnapping, Oneshot, Possessive Sans (Undertale), because i wrote it in a bout of inspiration, how DO I TAG HELP-, kinda!, like... literally dark not metaphorically dsfg, not... entirely sure what to call that..., ok idk what else so i'll leave it at that, possibly contains, the other two make a brief appearance.., this one's a bit err abstract? dksfj
Language: English
Status: Completed
Published: 2020-12-23
Updated: 2020-12-23
Packaged: 2021-03-10 22:53:35
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,527
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28264971
Author URL: https://archiveofourown.org/users/AKA_Indulgence/pseuds/AKA_Indulgence
Summary: You were thrown into some kind of void. After being chased by hoards of monsters, you find yourself in a dark forest.Something feels odd here... you hear a voice in the wind, calling out to you... what does it want?And why does it feel so right to walk deeper into the forest?
Relationships: Nightmare sans/reader, Sans (Undertale)/Reader
Comments: 28
Kudos: 172





	Dark Trees, Cold Barks, Flitting Shadows

**Author's Note:**

> HELO I just. Got randomly inspired to write this, so I did!
> 
> Here we have Nightmare luring you into his domain and lulling you to sleep. Hope you enjoy the snippet :>

You were running.

You were running as fast as your legs could take you, as hoards of black and white monsters chased after you.

_ You… you don’t know where you are. _

You were somehow thrown into some kind of weird dimension in between worlds. The monsters you see all look familiar, but none of them recognize you- all of them are moving to attack you, which has sent you running for escape, into what looks to be a big shaded place in the middle of whatever void you find yourself in.

You’re panting and it turns into a wheeze as you try to reach the edges of the forest ahead of you.

_ You don’t remember ever being so scared before. _

You make a cry of pain as you feel the burn in your legs  _ (this can’t be a dream. You wouldn’t feel this otherwise… this felt all too real.) _ as you make the final stretch to the gloomy, pitch-black line of trees. You throw yourself from the sterile white and into it, and keep running; you don’t know if they’ll follow you. After a few more moments of losing yourself in the trees do you finally turn around.

… Nothing.

No one followed you.

You could still see that white part of the void (anti-void?)... and it’s as if the monsters never existed, melted and evaporated into nothing. You take a rest, leaning your hand on the bark beside you, gulping air into your lungs as you gathered yourself. They went as fast as they came; you wondered in the vast white for quite a while when they slowly started climbing out of the ground(? If you could call it that) and showed you they weren’t the same as the peaceful monsters you met back home.

You turned around to the forest surrounding you, and the deeper you looked, the darker it seemed as the foliage got thicker.

You looked back at the white expanse behind you.

…

You think it’s best if you walked into the forest… you have a sudden anxiety gripping your insides, at the thought of those pale monsters somehow went through the barrier and followed you.

And even if they didn’t there was a feeling deep in your gut that going deeper was the right decision. Having trees- creepy, twisting, black trees- was  _ something _ as opposed to the vast nothing outside.

You felt around your pockets, finding the portable flashlight you had on you before you got thrown here. You turned it on.

The trees looked like they stayed just as dark… maybe a little lighter than before when you shone the light on them. The ground looked like regular dirt but more grey-scaled without any trace of earth on it. You try to take a closer look at the bark and find that it has an almost matte quality to it. The bark…  _ resembles _ normal bark, but it was smoother, like there was paint covering it. It felt strangely cool to the touch… you shiver when you pull your hand away.

You’d rather  _ not _ go deeper into the mystery creepy forest, but, you had nowhere else to go, nothing else to do. The void was, well, devoid of anything helpful, and going out might attract more of those monsters. And again, that feeling inside you.

_ Keep going. There might be a way out! _

  
  


Yeah. It’s better than not doing anything. You shone the light to where the thicker foliage seemed to be, and you walked.

And walked.

And walked.

And walked…

…

The burning in your arms and legs from all the running you did earlier turned into a cool sensation on your skin, like a fog settling. It got inexplicably colder the further you went, and as much as you wanted to turn around, you have no idea what way you came from. All the trees just… blend together, with what looked like sunlight(..? It couldn’t be. You were in some kind of pocket dimension. There’s no sun here…) peeking through the vegetation above you. Everything looked so monochromatic. It confused you. The deeper you went the stronger two feelings grew inside of you: One telling you  _ this is wrong, something’s wrong, you have to get out get out GET OUT! _ And another saying  _ Keep going! Going back now won’t do you much good, who knows what you’ll find if you keep going? _

No matter which you felt the strongest, the only option was to keep going. So you did.

… It felt like the ‘light’ was getting dimmer, becoming scarce. You could tell the trees apart, some of them even becoming less pitch-black and more grey, but that didn’t really tell you anything.

It’s quiet here. It was almost deafening now; the only sounds you could really pay attention to were your quiet breathing, your dull steps against the ground. It was so quiet to the point that when any other sound started to… warp.

_ The rustling of the leaves… was it because of the silence, or do they sound like whispers? _ You can’t figure out what it’s saying.

And the winds…

It… it almost sounds like a breath.

Getting louder and louder the longer you walk… until the wind carries a  _ voice. _

_ “Oh… what’s this?” _

You almost jump out of your skin when you hear it.

_ “What do I have here? A little human wondering around my forest…” _

Another ‘wind’ comes by, and what sounds to be a long, drawn-out, gratified sigh drifts into your ear, and sends a chill up your spine.

You turn around frantic, trying to figure out where the voice is coming from.

All you get is a deep, smooth chuckle in return.

_ “Oh… poor, sweet thing…” _ He (it sounded like a “he” at least) murmurs, a hint of patronization in his voice.  _ “Are you lost, little thing? You must be so lonely… afraid…” _

He continues in a sing-song voice.  _ “It’s ok. I’m here now.” _

Out of the corner of your eye, you see something move, and you quickly whip around to look at it, only to find it isn’t there anymore.

You swallow, shining the light on where you saw them last. “Wh… wh-who’s there?” despite your best efforts, your voice shakes, and even the beam of light is trembling because of your hand.

A shadow glides in from tree to tree beside you, and you try to follow its movements.

_ “Me?” _ another chuckle.  _ “Oh… I’m just... a  _ friend _.” _

There’s a smile in his voice, and he sounds almost teasing. Playful.

_ “You look so scared, love…” _ he murmurs.  _ “Don’t be. You’re with me now. Nothing can touch you while I’m here… you’re safe, and sound.” _

The voice echoes in your head, along with the voice you know is coming from the outside it makes your head hurt the more you try to reject the voice, the more you try to drive it out of your head. He’s getting under your skin and there’s something behind the voice. Something… possessive.

_ “Trust me, my dear…” _

“... N… no…” you shake, “No I don’t… I-I can’t… who are you??”

Another small laugh.

_ “I go by many names… but that’s not important.” _

You want to protest,  _ how can you trust him when you don’t even know who he is? _ But he continues.

_ “Aren’t you tired… little firefly?” _ another whisper wafts into you. The nicknames… they sound almost affectionate. There’s a lilt in his voice whenever he refers to you, like if you could see him, the edges of his smile would lift.

_ “It’s ok, sweet thing… you can rest. You can sleep.” _

Another sigh.

_ “I know you want to sleep… you’re so tired.” _

“No! No I’m… I’m not…” you try to protest, but as you try to find whatever it is that keeps flying from tree to tree, moving out of sight whenever you shine your flashlight on them, you feel your eyelids droop.

_ W… what… _

You… you feel so tired… why does it feel like all your muscles suddenly got so heavy? The portable flashlight feels like its turned into a dumbbell. Even as you try to wake yourself up, you yawn. Your eyelids droop and you lean forward…

… _Wait… no no STOP!_ _Wake up!_ You tell yourself, but all you manage is a small jolt.

A mist appears in the air, and it chases away the fear and distrust inside you.

_ “It’s ok. It’s ok to rest. You’re so tired. You can sleep here… go to sleep.” _ The voice calls out to you.

_ Sleep… sleep… sleep… _

The more he says it, the more it sounds like a command.

And you can’t even focus on staying awake, because that voice… it’s like it's invaded inside you and massaging your entire body, loosening your taut muscles as a warmth appears in your chest, spreading all throughout you.

_ “There we go… there we go, good girl…” _ the voice praises, and something in you  _ sings _ at it, your arms drooping to your sides and your flashlight falls out of your lax fingers. It rolls on the ground for a while before stopping; its light inexplicably going out as whatever was hiding behind the trees slowly makes their way to you.

_ Step step step. _

_ Closer. _

Your eyelids… they feel so heavy…

_ “Doesn’t it feel nice to give in, my darling?” _ the voice is giddy now, holding such…  _ affection _ in it.

“I’m…” you struggle to speak, even slurring a little. “I’mh…. not… sleep...sleepy….”

Your legs give out under you and your knees buckle, sending you falling-

Right into his arms.

* * *

Nightmare grins at his reward. He leans you in one of his arms, his other one circling your waist. You blink blearily up at him, like you’re trying to make out what he looks like.

_ You see a sheen off his black body… a wide, triumphant grin on his face and a cyan eye burning right into your soul. _

He brushes your hair off your face and strokes your cheeks lovingly with the back of his knuckles.

“You fought so hard, for a little thing.” he croons. “You didn’t have to do that.”

_ Either way, he would’ve gotten what he wanted. _

He sinks his hand into your hair, brushing it, feeling the delicate, delicate softness of each strand.  _ Just like silk. _ Your eyes flutter shut at the touch and he gently scratched your scalp, pulling his hand away with a few strands of hair following before falling back. He traces a phalange from your temples down to your chin, admiring your face.

_ You looked so soft. So…  _ lovely. _ There was warmth under those cheeks- those adorable, plump cheeks. Your eyelids were shut… they look like delicate flower petals, if you weren’t under his spell, he’d be afraid to wake you up. Your lashes just added to your beauty, catching the dim light that came drifting down through the leaves. Your nose was so cute too, he wanted to pinch it. If he brings his hand closer to your neck, he could feel your pulse… a sign that your wonderful heart carried life with it. _

_ Humans were so curious. _

His hand trailed away from your neck and up your chin, and he found himself staring at your lips for… a while, at least. They were so luscious. It shimmers a little under the light and… his thumb slides onto it. He so carefully traces your lips… giving it a little tug to feel how it gives under his phalange.

_ So… frail... _

His breath shakes, those lips look so  _ wonderfully inviting. He just wanted to press his teeth to them, taste how sweet you are, feel that soft warmth on his mouth- _

Nightmare stops himself when he senses…  _ others _ stepping into the forest, uninvited. He doesn’t enjoy anyone intruding in this private moment with you, but he isn’t too worried. He cradles your sleepy form in his arms and gently floats his way up a tree, before settling himself on a branch.

_ “(y/n)!” _

Slowly, like handling a baby, he lifts you up from his lap as his four tentacles extend from behind him, slowly placing you into them.

_ “Sans, don’t stray too far from me, you’ll get lost!” _

_ “dream, please… i  _ **_need_ ** _ to find her- (y/n)!!!” _

Nightmare leans closer to you. “Shut your eyes, pet.” he whispers, “you can sleep with me around.  _ Trust me.” _

_ “Sans please, this forest belongs to  _ him _ , we have to be careful…” _

_ “don’t you get it? it’s exactly because of that that i’m so  _ **_scared!_ ** _ she- he could’ve taken her-!” _

_ Sans moves in blind directions while Dream trailed him nervously, his bow and arrow ready on the side should his brother appear to them. They step into a clearing, even as the leaves shroud the ‘sky’, leaving only a few spots where light could penetrate. _

_ “please… please… (y/n)!” Sans’ throat is hoarse with desperation. “t… tell me you’re here!” _

_ … There’s no answer. He lowers his hands from his mouth and slouches as tears stream from his face. Dream slowly, quietly, gently places a hand on his shoulder. _

_ “... We haven’t looked everywhere. C’mon, we can’t give up yet, let’s keep looking.” _

_ This time, Dream leads on, his glow causing some stray, colorful flowers to bloom on the forest floor. Sans wipes his tears away with his sleeve as he takes a breath. He has to hold onto hope. He starts walking again, following after Dream. _

…

Nightmare smirks as he watches the two figures leave, below him. He exhales and slowly leans back onto the trunk of the tree, waiting until their footsteps fade into nothing.

… below him, you sway gently in two of his tentacles, like you were being rocked in a cradle. His tentacles both support your head and upper back and legs, where they meet in the middle around your waist and wind around you.

An eerie tune comes out his throat as a hum, placing his head in a propped up elbow as he watches you with one hooded socket, your sleeping form. So blissfully unaware, your so-called “saviors” having just stood right below you before moving on.

You looked so cute, a little sleepy smile playing on your lips. Your body sagged against his tentacles, and his other extended towards you, craving you just like himself. As you sway and rock under the tree branch his tentacles crept to your face and your arm; the one on your face sliding down your cheek and tickling your chin while the other slithered down your arm, roving all over your middle and stroking your thigh.

A tentacle briefly coiled itself around your neck before unwinding, and he starts to pet your hair with it. Nightmare smiles as he sees the little bits of his ooze dripping, coating your skin just a little… leaving a mark on you.

_ A being of light like yourself being touched by his darkness…  _ it sent happy tingles through his body.

  
_ “Shut your eyes… you can sleep while I’m around… you have no need to worry or fear.”  _ Nightmare croons as he watches your expression become even more relaxed, leaning into his petting tentacle.  _ “No one, nothing can hurt you here… trust me…  _ give in to me _ and I’ll keep you safe and sound.” _

**Author's Note:**

> There's... a fic idea in there somewhere... I just. Don't know,,, dshfklgfg I was thinking about Nightmare and there's a scene from a movie that inspired me and the image of Nightmare suspending you above the ground in his tentacles while he watches you *dreamily* (ha) made me go "Yes. I write that now." jkahs
> 
> I'll probably not write more but I hope it was a good read, which by the way, thanks for reading! A comment would be greatly appreciated :D
> 
> [Tumblr!](https://aka-indulgence.tumblr.com/)


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